Have either of you performed a top chop? I haven't.
But I was reading the little car mags in the 50s. It can turn out good or bad, depending.
There're slant chops, forward and back. Various ways to accommodate the tumblehome. With VWs you can do a Leatherman chop, where you quarter the body and narrow it.
One of the best chops I've seen had the B-pillar cut a fraction less than the A- and C-pillars. This bowed the B-pillar out slightly but noticeably.
That why you position the roof and fit the doors to it.